DE2423284A1 - METHOD FOR FLOCKING FLAKE TEXTILE SUBSTRATES - Google Patents

Description

BASF Aktiengesellschaft

Our reference: OZ 30 515F TrJd / Ri 67OO Ludwigshafen, 13.5

Process for flocking flat textile substrates

It has long been known that flat textile substrates such as woven, knitted or non-woven fabrics with a fine Paserflor can be used can be provided by the structure first with an aqueous polymer dispersion, which is generally a thickener contains, and which acts as an adhesive, thinly coated and then pastes from about 0.1 to 20 mm, in particular from 0.3 to 3 mm in length applies evenly and dries. The main fibers used for this are those made of viscose, cellulose and synthetic polyamides, such as polyhexamethylene adipamide and polycaprolactam in question. The fibers are generally applied electrostatically, whereby the fibers are accelerated in an electric field in the direction of the adhesive application and to a certain extent in this be shot into it. Furthermore, the fibers can be applied mechanically, e.g. with a vibrating sieve or by inflating with a stream of air, but felt-like flocks are obtained.

In these known methods of flocking, however, it is necessary Use relatively highly viscous polymer dispersions as an adhesive in order to prevent the adhesive from penetrating too deeply to prevent in the textile fabric. This occurs when the polymer dispersions are applied and conveyed Difficulties arise. In addition, the handle of the flockings obtained by this process is usually too little "textile".

It has now been found that flat textile substrates by applying a thin layer of an aqueous polymer dispersion, followed by flocking and drying can produce the flocked substrate at elevated temperature to about 200 ⁰ C with advantage when the text lien substrates a thin layer a heat-sensitized aqueous polymer dispersion and simultaneouslyJhit its application or directly

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then the application of the dispersion in its area adjoining the textile substrate by heating the textile substrate gels forth, in such a way that the one facing away from the textile substrate Area not gelled, flocked in the usual way and then dried at elevated temperature.

The new process can be based on the flat substrates customary for flocking, for example woven, knitted and nonwovens. The polymers contained in the aqueous polymer dispersions used for coating the flat substrates, which have adhesive properties, also practically do not differ from the polymers contained in such polymer dispersions which are used for conventional flocking processes. In general, however, polymer dispersions can be used in the new process which have a lower viscosity than would be required for the conventional flocking process. However, a lower viscosity of the polymer dispersions is not necessary, but it is usually sufficient to add smaller amounts of conventional thickening agents, such as methyl cellulose. In some cases it is also not necessary to add thickeners to the aqueous polymer dispersions. The aqueous polymer dispersions which are suitable for the process and which give polymer films which are tacky at room temperature can be prepared in a manner customary per se using the customary amounts of emulsifying and / or dispersing auxiliaries.

They are mostly derived from acrylic and / or methacrylic esters containing 1 to 12, in particular 1 to 8, alkanols, such as n-butyl acrylate, 2-ethylhexyl methacrylate and acrylate and n-butyl methacrylate, and often contain small amounts of polar groups ^; Comonomers, ego ^ ß-olefinically unsaturated mono- and / or dicarboxylic acids usually containing 3 to 5 carbon atoms, such as especially acrylic acid, methacrylic acid, crotonic acid, itaconic acid or maleic acid or their amides or N-alkoxyamides such as especially acrylamide, methacrylamide, N-methylol acrylamide and or N-methylolmethacrylamide and polymerized / in amounts of about 10 to 30 wt.% vinyl acetate, styrene and / or acrylonitrile. Butadiene-styrene copolymers, which contain small amounts, for example 0.5 to 5 _{3 ins-}

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special 1 to 3 wt. % polar group-containing monomers, such as Ο, β-monoolefinically unsaturated, mostly 3 to 5 carbon atoms containing mono- and / or dicarboxylic acids, such as acrylic acid, methacrylic acid or itaconic acid or their amides optionally substituted by alkoxy groups are well suited. The copolymers generally have glass transition temperatures below 30 ⁰ C ₃ usually below 20 ⁰ C. suitable for the preparation of polymer dispersions in question anionic and / or nonionic emulsifiers are, for example in the book by Houber-Weyl "Methoden der Organischen Chemie" , Vol. XIV / 1, Macromolecular substances, Georg Thieme Verlag, Stuttgart 1961, pages 192 to described in detail. The polymer dispersions suitable for the new process should, however, in contrast to the polymer dispersions suitable for the conventional flocking process, be heat-sensitive, ie gel as quickly as possible at elevated temperatures, which are usually above 40.degree. Heat sensitizers for the polymer dispersions are, for example, according to German Patent 869 86I and DT-OS

1 569 119 polyvinyl alkyl ethers, according to DT-AS 1 66 734 water-soluble Polyacetals, oxalkylated according to British Patent 1 206 Ο36, German Patent 1 2M3 394 and DT-OS 2 005 974 Polysiloxanes, according to DT-OS 1,619,049, 1,619,050 and 1,9 * »8 cation-active substances and, with particular advantage, alkoxylated amines with inverse solubility according to DT-AS 2 226 269 in question. If polymer dispersions which contain alkoxylated amines with inverse solubility are used, these show when used for the new process preferably a pH value below .6, mostly below 4 and in particular from 1 to 3. The polymer content the suitable dispersions in the new process is usually between 20 and 65, in particular between 40 and 60 percent by weight. If the heat-sensitized polymer dispersions contain oxyalkylated amines as sensitizers inverse solubility, their content, based on the polymers, is usually between 1 and 20 wt. #, preferably between

2 and 10% by weight . As the aqueous dispersion further -polymerizates are also those of ethylene-vinyl acetate copolymers in question, in which the molar ratio of ethylene to vinyl acetate from 20 to 80 and 70 is to 30th

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The heat-sensitive aqueous polymer dispersions can be applied to the flat substrates in a manner customary per se on a coating machine with a doctor blade or rollers or, furthermore, by spraying. In general, application quantities of 250 to 400, in particular 300 to 350 g of adhesive / m ² have proven useful.

In the new process, the application of the dispersion is to be heated by the flat substrate in such a way that the application of dispersion gels in the direction of its surface without, however, gelling the area of the application of the dispersion facing away from the textile substrate. It is generally sufficient if a few percent, for example 5 to 10 % of the thickness of the dispersion application is gelled from the flat substrate, but up to 80 % can also be gelled. However, it must be avoided that the application of the dispersion gels completely, since otherwise the fibers can no longer be adequately anchored. The sketch attached as an appendix makes this clear: This sketch shows a section through a flat substrate coated with an aqueous polymer dispersion. In this context, (1) means the flat substrate, (2) the dispersion application which has penetrated somewhat into the flat substrate and (3) the portion of the dispersion application that has gelled after the action of heat due to (1).

The application of the dispersion can be heated, for example, by adding the heat-sensitized aqueous polymer dispersion applied to a sufficiently preheated flat substrate. But you can also first of all on the flat substrate Apply the heat-sensitized aqueous polymer dispersion and then through the flat substrate, e.g. under Using ultrared heaters, hot air, hot rollers or a heated conveyor belt. To a To achieve gelling of the dispersion application in the specified area, it is necessary that the through the two-dimensional The amount of heat transferred to the substrate is sufficient to heat the dispersion application in the desired strength range up to the temperature at which the gelation takes place. This temperature and thus the required amount of heat is of

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depends on the sensitizer used and varies from case to case. Mostly one uses such sensitizers, in which gelation occurs at temperatures from about 40 to 90 ° C takes place »

Subsequent to the partial gelation of the dispersion application takes place the flocking of the coated flat substrate in a conventional manner, in particular by the electrostatic method Flocking, whereby the fibers customary for flocking flat structures, which usually have a length of 0.1 to 20 mm, in particular from 0.3 to 3 mm and a thickness of 15 to 3 den, can be used.

The flocked substrate sheet is then located in the usual way in itself at elevated temperature which may be up to about 200 ⁰ C, and usually between 140 and 16O ° C, dried.

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Claims (1)

O.Z. 30 515 Claim Process for flocking flat textile substrates by applying a thin layer of an aqueous polymer dispersion, then flocking and drying the flocked substrate at an elevated temperature of up to about 200 C, characterized in that a thin layer of a heat-sensitized aqueous polymer is applied to the textile substrates. Applies dispersion and simultaneously with the application or immediately afterwards the dispersion application gels in its area adjacent to the textile substrate by heating from the textile substrate, in such a way that the area facing away from the textile substrate does not gel, flocked in the usual manner and then added increased temperature dries. BASF Aktiengesellschaft. / Sign. 509849/0410